Bored piers and screw piles are both deep foundation systems used in Melbourne construction, but they are designed for very different applications. Bored piers are drilled and filled with reinforced concrete — suited to the heavy structural loads of homes, townhouses, and commercial buildings on Melbourne's reactive clay soils. Screw piles use helical steel sections screwed into the ground without concrete — suited to lighter structures. Your structural engineer's footing design specifies which one your project needs.
ASAP Piling installs bored pier foundations. We do not install screw piles. This article gives you an accurate, straightforward comparison so you understand why your engineer has recommended what they have — or to help you ask the right questions at the planning stage.
What Are Bored Piers?
Bored piers are reinforced concrete foundation elements installed by drilling a hole to the required depth, lowering a steel reinforcement cage, and filling the hole with concrete. The pile carries the building's weight from the footing system down through soft or reactive surface soil to stable ground below.
In Melbourne, bored piers are the standard deep foundation for:
- New homes and townhouses on reactive clay sites
- Multi-unit residential developments
- Commercial and industrial buildings
- Basement retention walls
What Are Screw Piles?
Screw piles — also called helical piles — are steel pipe sections with helical steel plates welded around the shaft. They are installed by rotating the pile into the ground using a hydraulic torque head on an excavator. No drilling, no concrete — the steel section is the structural element.
Screw piles are appropriate for:
- Residential decks, pergolas, and verandahs
- Temporary or relocatable buildings
- Lightweight steel-framed structures
- Solar panel foundations
- Situations where a concrete truck cannot reach the site
The Key Differences
| Factor | Bored Piers | Screw Piles |
|---|---|---|
| Load Capacity | High — suited to all residential and commercial building loads | Lower — suited to light structures only |
| Depth | 3 to 20+ metres — can reach deep stable ground | Typically 2 to 8 metres |
| Soil Suitability | All soil types including reactive clay, soft clay, and rock | Best in soft to medium soils — not suitable for hard rock or very stiff clay |
| Concrete | Reinforced concrete pile — durable and engineered | No concrete — steel only |
| Melbourne Clay | Standard solution for reactive clay sites across Melbourne | Rarely specified by engineers for principal structures in Melbourne clay |
| ASAP Piling | Yes — bored piers since 2001 | No — ASAP Piling does not install screw piles |
Who Decides — You or Your Engineer?
Your structural engineer decides. The engineer reviews the soil investigation, the building's loads, and the site conditions, then specifies the pile type, diameter, depth, and reinforcement. You do not choose between bored piers and screw piles — the engineer's footing design makes that call.
If your site has reactive clay soil — common across Melbourne's south-eastern, eastern, and bayside suburbs — your engineer will almost certainly specify bored piers for any home or commercial structure. If you don't yet have a soil report or structural engineer, call Nick on 0499 888 799. ASAP Piling can advise on what's typical for your suburb and refer you to geotechnical engineers.
Frequently Asked Questions
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